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Gastrulation is the stage in the early embryonic development of most animals, during which the blastula, or in mammals the blastocyst is reorganized into a multilayered structure known as the gastrula. Before gastrulation, the embryo is a continuous epithelial sheet of cells; by the end of gastrulation, the embryo has begun differentiation to establish distinct cell lineages, set up the basic axes of the body, and internalized one or more cell types including the prospective gut.
The blastocoel, also spelled blastocoele and blastocele, and also called cleavage cavity, or segmentation cavity is a fluid-filled or yolk-filled cavity that forms in the blastula during very early embryonic development. At this stage in mammals the blastula develops into the blastocyst containing an inner cell mass, and outer trophectoderm.
A germ layer is a primary layer of cells that forms during embryonic development. The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans produce two or three primary germ layers. Some animals, like cnidarians, produce two germ layers making them diploblastic. Other animals such as bilaterians produce a third layer between these two layers, making them triploblastic. Germ layers eventually give rise to all of an animal's tissues and organs through the process of organogenesis.
Organogenesis is the phase of embryonic development that starts at the end of gastrulation and continues until birth. During organogenesis, the three germ layers formed from gastrulation form the internal organs of the organism.
The Wnt signaling pathways are a group of signal transduction pathways which begin with proteins that pass signals into a cell through cell surface receptors. The name Wnt is a portmanteau created from the names Wingless and Int-1. Wnt signaling pathways use either nearby cell-cell communication (paracrine) or same-cell communication (autocrine). They are highly evolutionarily conserved in animals, which means they are similar across animal species from fruit flies to humans.
The primitive streak is a structure that forms in the early embryo in amniotes. In amphibians the equivalent structure is the blastopore. During early embryonic development, the embryonic disc becomes oval shaped, and then pear-shaped with the broad end towards the anterior, and the narrower region projected to the posterior. The primitive streak forms a longitudinal midline structure in the narrower posterior (caudal) region of the developing embryo on its dorsal side. At first formation the primitive streak extends for half the length of the embryo. In the human embryo this appears by stage 6, about 17 days.
Catenin beta-1, also known as β-catenin (beta-catenin), is a protein that in humans is encoded by the CTNNB1 gene.
Mesenchyme is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every organ in the developing embryo.
In the field of developmental biology, regional differentiation is the process by which different areas are identified in the development of the early embryo. The process by which the cells become specified differs between organisms.
Cripto is an EGF-CFC or epidermal growth factor-CFC, which is encoded by the Cryptic family 1 gene. Cryptic family protein 1B is a protein that in humans is encoded by the CFC1B gene. Cryptic family protein 1B acts as a receptor for the TGF beta signaling pathway. It has been associated with the translation of an extracellular protein for this pathway. The extracellular protein which Cripto encodes plays a crucial role in the development of left and right division of symmetry.
The development of fishes is unique in some specific aspects compared to the development of other animals.
Segment polarity protein dishevelled homolog DVL-1 is a protein that in humans is encoded by the DVL1 gene.
Nodal homolog is a secretory protein that in humans is encoded by the NODAL gene which is located on chromosome 10q22.1. It belongs to the transforming growth factor beta superfamily. Like many other members of this superfamily it is involved in cell differentiation in early embryogenesis, playing a key role in signal transfer from the primitive node, in the anterior primitive streak, to lateral plate mesoderm (LPM).
Dishevelled (Dsh) is a family of proteins involved in canonical and non-canonical Wnt signalling pathways. Dsh is a cytoplasmic phosphoprotein that acts directly downstream of frizzled receptors. It takes its name from its initial discovery in flies, where a mutation in the dishevelled gene was observed to cause improper orientation of body and wing hairs. There are vertebrate homologs in zebrafish, Xenopus (Xdsh), mice and humans. Dsh relays complex Wnt signals in tissues and cells, in normal and abnormal contexts. It is thought to interact with the SPATS1 protein when regulating the Wnt Signalling pathway.
Symmetry breaking in biology is the process by which uniformity is broken, or the number of points to view invariance are reduced, to generate a more structured and improbable state. Symmetry breaking is the event where symmetry along a particular axis is lost to establish a polarity. Polarity is a measure for a biological system to distinguish poles along an axis. This measure is important because it is the first step to building complexity. For example, during organismal development, one of the first steps for the embryo is to distinguish its dorsal-ventral axis. The symmetry-breaking event that occurs here will determine which end of this axis will be the ventral side, and which end will be the dorsal side. Once this distinction is made, then all the structures that are located along this axis can develop at the proper location. As an example, during human development, the embryo needs to establish where is ‘back’ and where is ‘front’ before complex structures, such as the spine and lungs, can develop in the right location. This relationship between symmetry breaking and complexity was articulated by P.W. Anderson. He speculated that increasing levels of broken symmetry in many-body systems correlates with increasing complexity and functional specialization. In a biological perspective, the more complex an organism is, the higher number of symmetry-breaking events can be found.
The Nodal signaling pathway is a signal transduction pathway important in regional and cellular differentiation during embryonic development.
Ingression is one of the many changes in the location or relative position of cells that takes place during the gastrulation stage of embryonic development. It produces an animal's mesenchymal cells at the onset of gastrulation. During the epithelial–mesenchymal transition (EMT), the primary mesenchyme cells (PMCs) detach from the epithelium and become internalized mesenchyme cells that can migrate freely.
The TCF/LEF family is a group of genes that encode transcription factors which bind to DNA through a SOX-like high mobility group domain. They are involved in the Wnt signaling pathway, particularly during embryonic and stem-cell development, but also had been found to play a role in cancer and diabetes. TCF/LEF factors recruit the coactivator beta-catenin to enhancer elements of genes they target. They can also recruit members of the Groucho family of corepressors.
Kang-Yell Choi is a professor of biotechnology at Yonsei University, and has a joint appointment position as a CEO of CK Regeon Inc. in Seoul, Korea. He has been performing researches related to cellular signaling, especially for the Wnt/β-catenin pathway involving various pathophysiologies. Choi has been leading the Translational Research Center for Protein Function Control (TRCP), a Korean government supported drug development institute, as a director for 10 years. Choi has been carrying out R&D to develop agents controlling the Wnt/β-catenin signaling pathway. Choi's main interest is development of the agents to treat intractable diseases that suppress tissue regeneration system through overexpression of CXXC5 and subsequent suppression of the Wnt/β-catenin signaling.
Dishevelled binding antagonist of beta catenin 1 is a protein that in humans is encoded by the DACT1 gene. Dact1 was originally described in 2002 as a negative regulator of Wnt signaling by binding and destabilizing Dishevelled. More recent investigation into the molecular function of Dact1 has identified its principle role in the cell as a scaffold to generate membrane-less biomolecular condensates through liquid-liquid phase separation. Mutations in the phase-separating regions of Dact1 lead to Townes-Brock Syndrome 2 while its overexpression is associated with bone metastasis.
References
- ↑ "A Brief Overview Of Thomian Rugby By Sharm de Alwis". www.tyretracks.com. Retrieved 2011-12-20.
- ↑ "Athula Wikramanayake Professor". www.bio.miami.edu. Retrieved 2011-12-20.
- ↑ "Athula H. Wikramanayake". www.hawaii.edu. Retrieved 2011-12-20.
- ↑ "Athula Wikramanayake". search.engrant.com. Archived from the original on 2012-05-30. Retrieved 2011-12-20.
- ↑ "Seminars 2011 - 2012". www.sars.no/seminars. Retrieved 2011-12-20.
- ↑ "Awards and Recognition". as.miami.edu. Retrieved 2014-07-15.
- ↑ "Selected Grants". as.miami.edu. Retrieved 2014-07-15.
- ↑ "Selected Publications". www.as.miami.edu. Retrieved 2014-07-15.